INA16 - Welcome to Athens

The INA16 conference is taking place in Athens and to celebrate we are launching a significant addition to Nannotax. We have added a large set of descritptive terms to the database and you can use them to search for taxa by morphological characters and to help identify unknown species. Take a look at Advanced Search (also on the Tools Menu) or the page on Tagging, (also on the About Nannotax menu). (jeremy.young@ucl.ac.uk).

Citation: Braarudosphaeraceae Deflandre, 1947Rank: FamilyNotes & discussion: Only two extant species have been described and only one of these, B. bigelowii, is well-established, but the family has a geological record back to the Early Cretaceous including several genera and many species (e.g. Perch-Nielsen 1985a,b, Aubry 1989, Bown 2005). These include forms with heavily ornamented pentaliths and pentaliths with concave sides. They sometimes occur in enormous abundance in sediments suggesting that Braarudosphaera can form massive blooms (see Peleo-Alampay et al. 1999). At present day, Braarudosphaera occurs sporadically in shelf environments, usually under conditions of lowered salinity.Affinities: Braarudosphaera was long considered a group of highly uncertain affinities and possibly dinoflagellates, but recent molecular genetic data (Takano et al. 2006) has shown that they occupy a basal position within the coccolithophore clade, and so are definitely haptophytes and probably derived in some way from coccolithophores.

Short diagnosis: Coccospheres pentagonal dodecahedra formed of five pentagonal plates

Morphology remarks: Basic morphology: Cell is typically non-motile and entirely enclosed in an exotheca of twelve plates each with five-fold symmetry (pentaliths). Cells have frequently been isolated but have never grown in culture, they contain visible chloroplasts, so are not cysts or protozoa (Lefort 1972, pers. comms. Green, Probert, Hagino). Lefort (1972) observed, and illustrated, rare specimens of B. magnei with two apically placed, sub-equal flagella. Pentalith morphology: Pentaliths consist of five segments, each of which behaves as a discrete crystal-unit with c-axis parallel to edge of the pentalith. A lamellar substructure to the segments is consistently present. Ecology & Biogeography: Predominantly neritic both at the present day and in the fossil record.

Geological Range: Last occurrence (top): Extant Data source: Total of range of species in this databaseFirst occurrence (base): within Cenomanian Stage (93.90-100.50Ma, base in Cenomanian stage). Data source: Total of range of species in this database